1. Field of the Invention
The present invention relates to an image for forming apparatus in which the rotational driving of sheet transport rollers by a driving portion is stopped in the case where sheet jamming has been detected.
2. Description of the Related Art
An image forming apparatus such as a printer, a copy machine, or a compound machine generally has a configuration in which multiple sheet transport rollers are provided along a sheet transport path for guiding a sheet such as printing paper along a sheet transport direction, the transport timing of a sheet transported in the sheet transport path by the sheet transport rollers, which are rotationally driven by a driving portion, is detected, and sheet jamming is detected using the detected transport timing.
FIG. 14 is an illustrative diagram schematically showing the state in which a sheet B is transported from a sheet storage portion A1 toward a photosensitive drum A2 in a conventional image forming apparatus AA.
As shown in FIG. 14, the conventional image forming apparatus AA in which multiple sheet transport rollers A4 are provided along a sheet transport path A3 generally has a configuration in which, in the case where jamming (sheet jamming) of a sheet B that is transported in a sheet transport direction Y is detected using the transport timing detected by a sheet detection portion A5, the rotational driving of sheet transport rollers A4 by a driving portion A6 is stopped.
Also, a sheet removal job region α for removing the sheet B that was motionless when jamming was detected (e.g., a region for removing the sheet B that was motionless when jamming was detected by releasing an access cover A7 in the sheet transport path A3) is provided at one or more places in the sheet transport path A3.
FIGS. 15A and 15B are schematic perspective diagrams for describing the sheet removal job for removing the sheet B that was motionless when jamming was detected. FIG. 15A shows a state during the release of the access cover A7, and FIG. 15B shows a state in which the access cover A7 is released and the sheet B that was motionless when jamming was detected is being removed.
As shown in FIGS. 15A and 15B, the access cover A7 is configured so as to open and close the sheet removal job region α in the sheet transport path A3 for removing the sheet B. Specifically, the access cover A7 is able to slide with respect to an apparatus main body A0 of the image forming apparatus AA in a width direction W that is orthogonal to the axial direction of the sheet transport rollers A4 (depth direction X) and the vertical direction Z.
In the case where jamming of the sheet B has occurred in the image forming apparatus AA, a user releases the access cover A7 (see FIG. 15A) in order to remove the sheet B that was motionless when jamming was detected, and removes the sheet B that is visible when the access cover A7 is in the released state (see FIG. 15B).
However, depending on the position of the sheet B that was motionless when jamming was detected, there are cases where the sheet B is not visible even when the access cover A7 is released (i.e., the sheet B is not present in the sheet removal job region α in the sheet transport path A3 and cannot be found).
FIG. 16 is a schematic perspective diagram showing the state in which the sheet B that was motionless when jamming was detected is not visible even when the access cover A7 is released.
As shown in FIG. 16, in the case where the sheet B that was motionless when jamming was detected is not visible even when the access cover A7 is released, the user does not know where the sheet B is located, and therefore the recovery job for removing the sheet B and restarting the image forming operation becomes time-consuming.
Particularly in the case where the sheet removal job region α is provided at multiple places, and a consecutive image forming operation is performed for consecutively performing image formation on multiple sheets, the above-described problem becomes increasingly significant as the inter-sheet distance between a preceding sheet and a successive sheet decreases and the number of jammed sheets increases.
In view of this, as forced moving processing in which a sheet that was motionless when jamming was detected is forcibly moved to a predetermined position, JP 2007-316174A (hereinafter, referred to as Patent Document 1) discloses a configuration in which, in the case where the occurrence of jamming is detected, and the leading edge of a sheet has stopped between an image carrier and a fixing apparatus, the sheet is forcibly transported until a detecting means, which is for detecting whether a sheet has passed through a pair of registration rollers, has detected the passage of the trailing edge of the sheet.
However, in the configuration disclosed in Patent Document 1, forced moving processing is performed regardless of where the sheet that was motionless when jamming was detected is located in the sheet transport path in the sheet transport direction (e.g., even if the motionless sheet is present in a sheet removal job region in the sheet transport path), and therefore forced moving processing is sometimes needlessly performed. Also, even when forced moving processing is performed on a motionless sheet, the sheet is simply forcibly transported until the passage of the trailing edge of the sheet is detected by the detecting means, and it is not always true that the sheet becomes located in a sheet removal job region in the sheet transport path.
In view of this, an object of the present invention is to provide an image forming apparatus that can avoid the needless execution of forcible moving processing and can reliably cause a sheet that was motionless when jamming was detected to be located in a sheet removal job region in a sheet transport path.